Voltage-regulator.



W. S. BRALLEY.

VOLTAGE REGULATOR.

APPLIGATIO'N FILED JULY 30, 190B.

Patented Nov. 4, 1913.

, Inventor-z 4 WaILeI-SBraIIe b 5 M4 Sqhy.

2f Fig-4 m Witnesses:

comma PLANoannu CO.,WASHINCITON, D. c.

' UNITED STATEQFATENT oFFioE.

WALTER '8. IBBALLEY, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEGT ISIC COMPANY, A CORPORATION OF NEW YORK.

VOLTAGE-REGULATOR.

Specification of Letters Patent.

voltage drops, and vice versa.

7 It has been found that the most efiicient regulation can be secured by quickly shift-- ing the field resistance back and forth from a point considerably below what is actually necessary to produce the proper result, to a point considerably above such requirement. According to this principle, for example,-if a voltage should tend to rise above normal the regulator should at once decrease the excitation of the generator to an amountgreater than is necessary torestore the voltage to the normal, thereby instantlyv checking the rise of voltage and tending to depress the voltage below normal. Just as soon, however, as the voltage has assed the normal value and tends to fall low the same, the ator should act to increase 'the field excitation in the same manner to an amount greater than necessary to restore it to normal. This mode ofre'gulation necessitates a frequent operation of the regulator, but itreslrlts in a ,fairly steady char e of'potential in the Ina-in line to meet't e 1 changes in load.

- In order to produce considerable alterat1on ofresistance in the generator field circuit, I employ means for amplifying the ef fect of predetermined variations of voltage upon the regulator. v This'nieans may comone or more electrolytic cells of the aluminum type across the line and acting to vary the potentialinthe winding of a solenoid .which controls arheostat' in the field circuit. .The electrolytic cell has the ar ps yg i me aefiss a Substantial w of current up to a critical yoltage of about 420 volts, at which" p int its resistantfilmof aluminum. hydroxid suddenly gives way and 7 permits a-free flow of current. If the drops below 420, the film instantly reforms and sh uts ofi the current. It is thus posslble to get a wide range in current flow slight increase of potential across it-s ter'-' minals Wlll result 1n a large increase of current through the cell, and a slight decrease of potential across its terminals will be accompanied with corresponding large decrease of current through the cell. In other words, the changes in the value of the currents through a cell of this kind is greater Patented Nov. 4:, 1913.

with a small variation in voltage, for if'the 1 cell is operated near its critical voltage a than in a dead resistance, such as an iron rheo'stat, with the same change ofvoltage. This characteristic of a cell of this type enables me to impress upon the aforesaid solenoid sudden and considerable changes .of r

current which act correspondingly on the field rheostat and produce sudden and considerable changes in the excitation of the generator field. r

In the accompanying drawing Figure 1 1s a diagram showing one embodiment of my invention in a direct current system, Fig. 2 is the characteristic curve of an electrolytic cell, Fig. 3 shows the invention applied to an alternating current system, and Fig. 4 shows a modification.

Referring first to Fig. 1, the main lines 1 are supplied'with current from the genera- -t0r 2, whose shunt field winding 3 is in series with a rheostat, preferably a pile ofcarbon plates 4 with a lever 5 for varying the-pres sure on them and thereby varyingtheir re sistance. The lever. is urged down upon the plates by a spring 6, butcan lifted by a. sucking solenoid 7 whose .core 8 is attached to said lever. The solenoid is connected across the line in series with 'a variable resistor 9 and one or more electrolytic cells 10. A second adjustable resistor 11 is in series withthe resistor 9 and is parallel with the cells 10. The object of this arrangement of cellc incuitisconnectedcanbegivenaposolenoid cells and resistors is to get a varia- I tential lower than that of the line. The 2- sistance of the resistor 9 and the solenoid should be small as compared with that of the dow cells, probably about five per cent. of the cell resistance. .The smaller it is, the more sensitive will be the -regulator.

Fig. 2 shows the characteristic voltampere discharge of an j aluminum cell, which rises with only a-slight leakage current to a critical value. of about 420 volts at the point 'a where the resistant film sud denly o ens and permits a free flow of current. ny drop of the voltage below this critical point'causes the film to close again and, oppose its full resistance tothe current.

One, two or more cells may-be used in'series as may be required 'by' the' -line volta This sudden opening and' closing of t e solenoid circuit as the voltage fluctuates produces sudden andconsiderable changes pressure on the pile of carbon plates and thus correspondingly varies the current in the field circuit.- An increase in line voltage suflicient to carry 'it up over the unfstable point a ofthecurve in Fig. 2 will lievc the pressure on'the-carbon plates and increase the field circuit resistance, cutting down the'field excitation and reducing the voltage at the generator terminals, and .vice

whose field coils 13 are energized b an eitciter 14. Thevoltage on the main us bars- 15 is stepped downron' a potential transformer 16, whose secondary'l'l is in circuit with the solenoid18 and the electrolytic cells I 19, the carbon plate resistor20 in the exciterfield circuit being controlled 3 by .the' solenoid through the lever 21 and spring- 22, as in Fig. 1. The voltage impressed upon the solenoid and cell' circuit may be vh'r'ied by taps over thesecondary 17 ofthe potential transformer; 7

Fig. 4 shows ainodification in which the generator field'has a differential winding 23 in series with electrolytic cells 10*connected' g. 3 shows the application of the invention to alternating current generators 12 machine. r

ere'by reduces the output of the cluding the field winding thereof, an electrolytic cell of the aluminum type in said parallel circuit, and means for causin the variation ofcurrent in said parallel circuit to vary the magnetization produced by the field. winding. 7

2. The combination with an electric genera toijof a circuit parallel to the circuit'inthereof, an electrolytic cell, of the aluminum type in said cluding the field wind' paiglallel1 cirlcuittlzad and a coil.h in series with 'sai 'ce a ap to varye'm etizing effect of said-field windi agn 3. The combination wit an electric generator, of a 'rheostat in its field circuit, a, circuit in parallel with said field circuit including an electrolytic cell of the aluminum type, and means in circuit with said cell'for controlling said'rheostau 4. The combination with an electric generator,'of a rheostat' in its field circuit, a circuit in parallel withsaid field circuit including an electrolytic cell of the aluminum type, a solenoid in series with said cell and a means whereby said solenoid can operate said rheostat. '1

erator, of a rheostatin' its field circuit, and a circuit in. parallel 'th 'sa'id field circuit including an electro'] ic cell of the aluminuni type, a solenoidland a resistor in series with said cell, said solenoid controlling said rheostat, and -a second resistor in series with the first mentioned resistorand in parallel with said cell and solenoid. 1

6. In combination, a' d mo-electric machine, an electrolytic cc -'of the-aluminum type having im ressed thereon avoltage proportional to t e vol of said and means responsive to e current 5. The combination with an electric'gen saidcells forva'rying the excitation of ma Y 7. Incombination, a'

chine, a field winding for said mlchmfl, a

resistance included in'ci'rcuit with said and winding, an electrolytic of the alumi- 'nu'mtype'having thereon [voltage proportional .to e -vol 'ofsaid'rnachine,=-and means responsive to current through said cells for controlling said re- In witness whereofl l my hand this 29th da of'Jul 1908;

ili' nrunrm B. Hur.n,; 

